MySQL - add clauses to left join - mysql

Question

I have a table called properties (p) and another table called certificates (c). There can be more than one certificate allocated against each property or no certificate at all. I need to produce a query that uses a join and only displays one certificate from the certificates table per property. The one certificate that is shown needs to be the one with the most recent expiry date. There is a field in the certificates table named 'certificate_expiry_date'. The simple join would be p.property_id = c.certificate_property but this currently outputs all certificates.
My Query Attempt
Here's my query so far;
SELECT DISTINCT t.tenancy_property, t.*, p.*, c.* FROM tenancy t
INNER JOIN property p
on t.tenancy_property = p.property_id
LEFT JOIN
(
SELECT *
FROM certificate
WHERE certificate_expiry_date > CURDATE()
ORDER BY certificate_expiry_date DESC
LIMIT 1
) c ON p.property_id = c.certificate_property
WHERE t.tenancy_type='1' AND p.property_mains_gas_supply='1' AND p.property_availability='2' ORDER BY t.tenancy_id DESC LIMIT {$startpoint} , {$per_page}
This query executes fine but doesn't seem to take into account the left join on the certificates table.
Table structure for table certificate
CREATE TABLE IF NOT EXISTS `certificate` (
`certificate_id` int(11) NOT NULL AUTO_INCREMENT,
`certificate_property` int(11) DEFAULT NULL,
`certificate_type` tinyint(4) DEFAULT NULL,
`certificate_reference` varchar(255) COLLATE utf8_bin DEFAULT NULL,
`certificate_start_date` date DEFAULT NULL,
`certificate_expiry_date` date DEFAULT NULL,
`certificate_notes` text COLLATE utf8_bin,
`certificate_renewal_instructed` tinyint(4) DEFAULT NULL,
`certificate_renewal_contractor` int(11) DEFAULT NULL,
PRIMARY KEY (`certificate_id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_bin AUTO_INCREMENT=219 ;

Answer 1

If we only need to return one or two columns from the certificates table, we can sometimes use correlated subqueries in the SELECT list.
This approach has some performance implications for large tables; but for some use cases, with appropriate indexes available, this can be a workable approach.
SELECT p.id
, p.somecol
, ( SELECT c.col
FROM certificate c
WHERE c.property_id = p.id
ORDER BY c.date_added DESC, c.id DESC
LIMIT 1
) AS most_recent_cert_col
, ( SELECT c.date_added
FROM certificate c
WHERE c.property_id = p.id
ORDER BY c.date_added DESC, c.id DESC
LIMIT 1
) AS most_recent_cert_date_added
FROM property p
WHERE ...
ORDER BY ...

Answer 2

Updated answer with your updated information
Something like this?
(Note: This answer assumes that each property has at least one certificate, or else the sub-query qMostRecentExpire may fail)
select
p.property_id
, p.*
, ( select
c.certificate_id
from
certificates as c
where
c.certificate_property = p.property_id -- all the cert of this property
and c.certificate_expiry_date < CURDATE() -- cert has expired
order by c.certificate_expiry_date desc
limit 1 -- most recent one
) as qMostRecentExpire
from
properties as p
Updated answer after knowing that some properties may have no certificates
select
p.property_id
, p.*
, ( select
c.certificate_id
from
certificates as c
where
c.certificate_property = p.property_id -- all the cert of this property
and c.certificate_expiry_date < CURDATE() -- cert has expired
order by c.certificate_expiry_date desc
limit 1 -- most recent one
) as qMostRecentExpire
from
properties as p
, certificates as c -- inner join : properties that
where -- has not cert will be dropped
p.property_id = c.certificate_property